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The “last time” was 20 years after Mexico had secured their independence from Spain and a few years after fending the military was worn down fending off incursions from France. Mexico was barely able to control or defend northern territories from indigenous tribes at the time, never mind a full country’s military.
It was also nearly 180 years ago and has no bearing on modern conflict.
All those undocumented workers the US wants to keep out, they're really important to the US actually functioning.
Right now? Trump is risking a worldwar trying to save the dollar/energy/make the history books.
They can take Texas back while they're at it. Or perhaps Elon wants to take it.